This invention relates to an image forming process including a heating step, and more particularly, to a process for forming images by heating using a precursor of a development retarder.
Heat developable photosensitive materials and their image forming processes are well known in the art and described in the literature, inter alia, "Fundamentals of Photographic Engineering", Corona Publishing K.K., Tokyo, Japan (1979), pages 553-555; "Image Information", April 1978, page 40; and Nebletts Handbook of Photography and Reprography, 7th ed., Van Nostrand Reinhold Company, pages 32-33.
A number of methods have been proposed for producing color images through heat development, for example,
a process for forming color images using a coupler as a dye-providing substance (see U.S. Pat. Nos. 3,531,286; 3,761,270; and 4,021,240; Belgian Patent No. 802,519; and Research Disclosure, September 1975, pages 31-32),
a process of forming images using a dye having a nitrogen-containing heterocyclic group incorporated in its dye moiety as a dye-providing substance (see Research Disclosure, May 1978, pages 54-58, RD-16966),
a process based on silver dye bleaching (see Research Disclosure, April 1976, pages 30-32-, RD-14433; ibid, December 1976, pages 14-15, RD-15227; and U.S. Pat. No. 4,235,957), and
a process for forming a color image using a leuco dye (see U.S. Pat. Nos. 3,985,565 and 4,022,617).
These color image forming processes, however, have their own drawbacks and commonly suffer from the insufficient shelf storage of photosensitive material that the material deteriorates with a lapse of time as exemplified by increasing fog. Proposed as a solution of this problem is the use of a reducing dye-providing substance capable of releasing a hydrophilic dye as disclosed in Japanese Patent Application Kokai No. 58-58543. This proposal has succeeded in significantly overcoming the technical problems of the prior art processes.
Nevertheless, because of the absence of development inhibiting or retarding means, the aforementioned image forming processes based on heat development cannot avoid such problems as increasing fog due to overdevelopment and varying photographic performance due to varying heating temperature, and thus they are still difficult to always produce consistent images.
On the other hand, several development inhibiting techniques are known in the conventional diffusion transfer photography. For example, development inhibitor precursors and color diffusion transfer photographic materials using same are described in Japanese Patent Publication Nos. 60-19498 and 60-29709. These patents describe or suggest nowhere the application to heat developable photosensitive material. Quite unsatisfactory results could be obtained when the compounds disclosed in these patents are added to heat developable photosensitive material.